Tables shows repeat entries when sorted by descending value

[mhinc14]

I have a table (class) which has a column with a numeric value. When i sort the table by descending on this numeric value, a lot of the rows get repeated. for example my table has 500+ rows, when i scroll down from 500 to 300 the rows keep repeating so i can never scroll past 300.

There is a problem with how it is rendering virtualised lists.